Process for preparing fluorinated aliphatic compounds

ABSTRACT

A process is disclosed for the preparation of a fluorinated aliphatic olefin having the formula 
     
         CH.sub.a F.sub.3-a --CH.sub.2 --CH.sub.b F.sub.3-b 
    
     wherein a is 0 or the integer 1 or d and b is 0 or the integer 1, 2 or 3. 
     In the first step of the process, a chlorinated olefinic hydrocarbon of the formula 
     
         CH.sub.c Cl.sub.2-c ═CH--CH.sub.d Cl.sub.3-d 
    
     wherein c is 0 or the integer 1 and d is 0 or the integer 1 or 2 is reacted with anhydrous hydrogen fluoride for a period of time and at a temperature sufficient to form a chlorofluoro olefin of the formula 
     
         CH.sub.e Cl.sub.2-e ═CH--CH.sub.f F.sub.3-f 
    
     wherein e is 0 or the integer 1 and f is 0 or the integer 1 or 2. 
     The chlorofluoro olefin produced in the first step is then reacted with anhydrous hydrogen fluoride in a second reaction. This second reaction is catalyzed with at least one compound that is a metal oxide or metal halide. Mixtures of said metal oxides, metal halides and metal oxides with metal halides may also be used. The metallic part of such compound is arsenic, antimony, tin, boron or is selected from a metal in Group IVb, Vb. VIb. VIIb or VIIIb of the Periodic Table of the Elements. 
     The desired fluorinated aliphatic hydrocarbon is subsequently separated and recovered. 
     The process is particularly suitable for the preparation of 1,1,1,3,3-pentafluoropropane.

This application is a continuation of Ser. No. 08/559,779 filed Aug. 28,1995 now U.S. Pat. No. 5,616,819.

FIELD OF THE INVENTION

This invention relates to a process for preparing aliphatic compoundssubstituted with multiple fluorine atoms. In particular, this inventionrelates to the discovery that highly fluorinated aliphatic compounds canbe prepared in high yield by a two step process comprising anuncatalyzed halogen/fluorine exchange of an chlorinated olefin followedby a catalyzed hydrofluorination and halogen/fluorine exchange of theresulting chlorofluoro intermediate.

BACKGROUND OF THE INVENTION

The replacement of chlorofluorocarbons (CFC's) widely used inrefrigerant compositions, propellants and cooling fluids as well asblowing agents, solvents and rinse agents with environmentallyacceptable alternatives has produced an abundance of compounds meetingone or more of these needs. The most acceptable replacement compoundsare those having little or no chlorine, since it is generally acceptedthat chlorinated aliphatic hydrocarbons lead to unacceptably reactivechlorine-containing radicals when present in the upper atmosphere. Theseradicals are thought to react with the ozone in the stratospheredepleting it to dangerously low levels.

One of the more promising alternatives to CFC's are the aliphaticcompounds where chlorine has been replaced with fluorine. Thesematerials are known as hydrofluorocarbons (HFC's). Typical HFC's haveatmospheric lifetimes and global warming potentials that are a fractionof their chlorinated analogs. However, many of their other physicalproperties (low flammability and toxicity, sufficient volatility, etc.)are identical or similar to the CFC's. Accordingly, they are attractivereplacements for the chlorinated molecules.

In processes for preparing HFC's, a usual starting material is thechlorinated analog of the desired fluorinated compound. Thus, U.S. Pat.No. 2,787,646 discloses that SbF₃ Cl₂ and\or SbF₃ are useful forconverting compounds of the formula CMZ₂ CX═CHY, for example3,3,3-trichloroprop-1-ene or 1,1,3-trichloroprop-1-ene to compounds ofthe formula CF₃ CX═CHY, for example 3,3,3-trifluoroprop-1-ene.

U.S. Pat. No. 2,549,580 discloses the conversion of1,1-dichloroprop-1-ene to 1,1,1-trifluoropropane by means of hydrogenfluoride at 120° C. and 800 psi pressure.

The preparation of 1-chloro-1,1,3,3,3-pentafluoropropane and of1,1,1,3,3,3-hexafluoropropane from 1,1,1,3,3,3-hexachloropropane in theliquid phase is described in EPO Publication No. 0 522 639 A1. While thepreferred catalyst for the reaction is noted to be SbCl₅, othercatalysts disclosed are those metal chlorides, fluorides, and chloridefluorides of Group IIIa, IVa, IVb, Va, Vb and VIb of The Periodic Tableof the Elements.

Compounds such as 1,1,1,3,3,3-hexafluoropropane are prepared by thecoupling of two chlorine containing reactants, i.e.,1,1,1-trichloro-2,2,2-trifluoroethane and dichlorodifluoromethane, inthe presence of hydrogen and a first catalyst to form an olefin, i.e.,1,1,1,3,3-pentafluoro-2-chloroprop-2-ene and then hydrogenating theolefin in the presence of a second catalyst. See WO 95/05353.

SUMMARY

The process of the present invention to prepare a fluorinated aliphatichydrocarbon utilizes a chlorinated olefinic hydrocarbon as the startingmaterial The olefin has the formula

    CH.sub.c Cl.sub.2-c ═CH--CH.sub.d Cl.sub.3-d

wherein c is 0 or the integer 1 and d is 0 or the integer 1 or 2. In thefirst step of this process, the olefin is reacted with anhydroushydrogen fluoride (HF) for a time and at a temperature sufficient toform a second olefin where some of the chlorine atoms in the startingmaterial have been replaced with fluorine. The second olefin has theformula

    CH.sub.e Cl.sub.2-e ═CH--CH.sub.f F.sub.3-f

wherein e is 0 or the integer 1 and f is 0 or the integer 1 or 2. Thissecond olefin is then reacted with anhydrous HF to form the desiredfluorinated aliphatic hydrocarbon, i.e., a compound of the formula

    CH.sub.a F.sub.3-a --CH.sub.2 --CH.sub.b F.sub.3-b.

This reaction may be catalyzed with a catalytically effective amount ofat least one metal oxide or at least one metal halide. Mixtures of thesemetal oxides, metal halides or metal oxides with metal halides may alsobe advantageously used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The process of the present invention is particularly useful forproducing highly fluorinated aliphatic compounds that are not easilyprepared in typical fluorine-for-chlorine substitution reactions.

Thus, for example, in the catalyzed reaction of1,1,1,3,3-pentachloropropane with hydrogen fluoride, fluorinesubstitution for chlorine is accompanied by much tar and byproducts sothat the pentafluoro compound is not formed in commercially acceptableyields.

Similarly, polychloro olefins such as 1,1,3,3-tetrachloroprop-1-ene withanhydrous hydrogen fluoride and a typical catalyst fail to yield thedesired pentafluoropropane in acceptable yields due to extensive tarryresidue formation.

The process of the present invention overcomes these and otherdisadvantages by preparing in a first step a partially fluorinated,chloroolefin of the formula

    CH.sub.e Cl.sub.2-e ═CH--CH.sub.f F.sub.3-f

wherein e is 0 or the integer 1 and f is 0 or the integer 1 or 2 fromthe reaction of a polychloro compound of the formula

    CH.sub.c Cl.sub.2-c ═CH--CH.sub. Cl.sub.3-d

wherein c is 0 or the integer 1 and d is 0 or the integer 1 or 2 withanhydrous hydrogen fluoride. The reaction is carried out for a time andat a temperature sufficient to produce the partially fluorinated, chloroolefin, also referred to herein as a "chlorofluoro-olefin".

In the above-disclosed first step, it is preferred that the polychlorocompound is one where c is 0 or the integer 1 and d is the integer 1 or2. Most preferably, c is 0 and d is 1, or c is 1 and d is 0.

At least three moles of anhydrous hydrogen fluoride are required toproduce the partially fluorinated, chloro-olefin. However, an excess ofhydrogen fluoride, preferably from about 2 to about 10 times thestoichiometric requirements are typically used in this reaction tofacilitate the formation of the fluorochloro-olefin.

The reaction can be carried out as a batch or continuous process. In thebatch mode, the polychloro olefin starting material may be added to thereaction vessel first. Order of addition is not critical. Hydrogenfluoride is then introduced and the reaction vessel heated, withagitation, to a temperature and over a period of time sufficient toproduce the desired partially fluorinated olefin, i.e., a temperature offrom about 70° C. to about 120° C. preferably about 80° C. to about 100°C., for from about 15 minutes to about 24 hours. The pressure duringthis reaction step is maintained at 200-230 psia by means of a backpressure regulator and the HCl generated is vented through a refluxcondenser. HF and products carried along with the waste HCl arecondensed and returned to the reactor. Accordingly, the reaction is runin the liquid phase for convenience although the reaction may be run inthe vapor phase over an appropriate surface such as aluminum fluoride.This procedure is a conventional one and well known in the fluorinechemistry art

At the conclusion of the reaction, the reaction vessel is cooled,typically to about 50° C. and the partially fluorinated chloro-olefinand excess HF is then flash distilled. The resulting mixture is used "asis" without further purification for the second step of the process ofthe present invention.

The continuous mode requires continuous mixing at a flow rate andtemperature sufficient to assure the contact times at the temperaturerange noted above. Continuous removal of the fluorochloro product andthe by-product gases with HF is of course, required.

As noted herein, the chlorofluoro olefin collected from the firstreaction step is typically used without further purification in thesecond step of the process of the present invention. This second stepmay also require additional anhydrous hydrogen fluoride in the secondreaction vessel which, in this step, contains a catalyst. As in thefirst step, the reaction which is also carried out in the liquid phasewith removal of HCl or under autogenous pressure, can be in thecontinuous or in a batch mode. The catalyst is typically introduced intothe reaction vessel prior to the partially fluorinated, chloro olefinand HF.

A variety of catalysts (or mixtures of catalysts) are useful in carryingout the second step of the reaction of the present invention. To a largeextent, many of these catalysts are equivalent and the choice depends oncost, availability and solubility in the reaction mass. The catalystsare metal halides or oxides or mixtures of such compounds, the metalsbeing selected from the group consisting of arsenic, antimony, tin,boron, and from metals of Group IVb, Vb, VIb, VIIb, or VIIIb of thePeriodic Table of the Elements. Preferably the metal compound is achloride or fluoride, most preferably a fluoride. It is preferablyantimony, arsenic, tin, bismuth or from Group IVb or VIIIb of thePeriodic Table of the Elements. Preferably the catalyst is selected fromthe fluorides of antimony, tin, titanium and mixtures thereof. Mostpreferably, the catalyst is a mixture of antimony (V) and titanium (IV).While molar ratios of antimony to titanium of about 3 to about 5 may beused, it is especially preferred to use a molar ratio of antimony (V) totitanium (IV) in a 4 to 1.

The amount of catalyst used in the reaction is sufficient to catalyzethe reaction. It is at least 1 mmol and preferably about 10 to about 200mmol, per mole of partially fluorinated, chloro-olefin used in batchoperation. At very low concentrations of catalyst, the reaction of thesecond step may be unacceptably slow. A very high concentration ofcatalyst may be wasteful due to the fact that the solubility limit mayhave been reached in the reaction mass. Consequently, the most preferredamount of catalyst is from about 10 to about 50 mmol, per mole ofchlorofluoro olefin.

The second step of the reaction is conducted for a time and at atemperature sufficient to form the desired fluorinated aliphatichydrocarbon. This is typically in the range of from about 25° C. toabout 150° C. for about 15 minutes to about 24 hours. Preferably thereaction temperature is from about 75° C. to about 175° C. mostpreferably 80° C. to about 100° C. for from about 45 minutes to about 6hours. Higher temperatures (above 200° C.) are required for a vaporphase reaction.

During the second step of the reaction, a reaction mass is produced thatis essentially a mixture of the desired product (the fluorinatedaliphatic hydrocarbon), hydrogen fluoride, catalyst and very smallamounts of unreacted starting material from step i. ) and from stepii.). The components of the mixture are not readily separated from thefluorinated aliphatic hydrocarbon end product by conventional methods.

For example, conventional distillation does not result in a separationof the end product from hydrogen fluoride because these materials havesimilar boiling points. Liquid\liquid phase separation is impractical asthe two materials are miscible. The standard method for inducing phaseseparation (addition of an unreactive solvent that dissolves thefluorinated hydrocarbon, but not hydrogen fluoride) is not efficient.

It has now been discovered that the fluorinated aliphatic hydrocarboncan easily be separated from a hydrogen fluoride mixture, suchexemplified by the reaction mixture formed in step ii.) by adding tosuch mixture an organic or inorganic salt that preferentially dissolvesin the hydrogen fluoride and causes an insoluble liquid phasesubstantially enriched in the fluorinated aliphatic hydrocarbon toseparate.

In order to be effective in this separation process, the organic orinorganic salt must be unreactive to the components of the reactionmixture, sufficiently soluble in hydrogen fluoride, e.g., the reactionmixture, to cause the phase enriched with the fluorinated aliphatichydrocarbon to separate out as an easily recovered separate phase,relatively insoluble in the fluorinated hydrocarbon end product andreadily separated from the resulting residual mixture after thefluorinated aliphatic hydrocarbon has been separated.

The organic salts useful to effect such separation include ammonium andlower alkyl ammonium fluorides, e.g., ammonium fluoride and mono, di,tri or tetra C₁ to C₃ linear or branched alkyl ammonium fluorides.Preferably, such salts include ammonium fluoride, mono anddimethylammonium fluoride and mono and diethylammonium fluoride.Particularly useful is ammonium fluoride.

The inorganic salts useful to effect such separation process include thefluorides and the bifluorides (sometimes called "acid fluorides") of themetals of Group Ia of the Periodic Table of the Elements. Preferably thefluorides and acid fluorides of lithium, sodium and potassium are usedin this process. Most preferred are the fluorides of sodium andpotassium.

The quantity of organic or inorganic salt added to the reaction mass isdirectly proportional to the amount of fluorinated aliphatic hydrocarbonthat appears in the enriched, liquid separate phase. Thus, as little as0.01 mole of salt per mole of hydrogen fluoride (calculated) issufficient to result in the separation of a second liquid phase If morethan 0.25 mole of salt is used per mole of hydrogen fluoride(calculated), then crystallization of the reaction mixture may occur, (acrystalline complex is formed between the salt and hydrogen fluoride)interfering with separation of the desired product. Preferably the saltis used in an amount of 0.02 to about 0.20 mole per mole of hydrogenfluoride (calculated), most preferably about 0.05 to about 0.10 mole.

In the following examples, specific embodiments of the process of thepresent invention are disclosed. These are not included as limitationson the process but are for the purposes of illustration only. Unlessindicated otherwise, temperatures are degrees Centigrade.

EXAMPLES Example 1

Preparation of 1,1,1,3,3-tetrafluoropropane from1,1,3,3-tetrachloropropene via 1-chloro-3,3,3-trifluoropropene

i (Uncatalyzed)

Preparation of 1-chloro-3,3,3-trifluoropropene from1,1,3,3-tetrachloropropene

A 450 ml hastelloy autoclave, fitted with a condenser and back pressureregulator, was evacuated and cooled in a dry ice/acetone bath. Thecondenser was maintained at 0° C. The reactor was charged with 120 g (6mole) of anhydrous HF. The reactor was then charged with 180 g (1 mole)of 1,1,3,3-tetrachloropropene. The reactor was heated to 80° C. and thepressure maintained at 200 p.s.i. by venting HCl through the pressureregulator. When HCl evolution ceased, the reactor was cooled to 50° C.and discharged through a KOH scrubber and into a separatory funnel fullof ice. The product was decanted as the more dense layer into a chilledbottle.

An average isolated yield of 107 g (80%) was achieved for each of 4consecutive runs For each run, approximately 19 g of oligomeric materialwas recovered from the reactor.

ii (Catalyzed)

Preparation of 1-chloro-3,3,3-trifluoropropene from1,1,3,3-tetrachloropropene

(SbCl₅ Catalyzed)

A 450 ml hastelloy autoclave, fitted with a condenser and pressureregulator, was evacuated and cooled in a dry ice/acetone bath. Thecondenser was maintained at 0° C. The reactor was charged with 3 g (0.01mole) of SbCl₅ and 136 g (6.8 mole) of HF. The reactor was heated to 90°C. for 1 hour. The reactor was then cooled to 20° C. and the pressure ofHCl was released. The reactor was then cooled in a dry ice/acetone bathand charged with 152 g (0.84 mole) of 1,1,3,3-tetrachloropropene. Thereactor was maintained at 80° C. and the pressure maintained at 200p.s.i. by venting HCl through the pressure regulator. When HCl evolutionceased, the reactor was cooled to 50° C. and discharged through a KOHscrubber and into a separatory funnel full of ice. The product wasdecanted as the more dense layer into a chilled bottle.

A total of 3 g (2.6%) of 1-chloro-3,3,3-trifluoro-propene was isolated.After washing, 109 g of oligomeric material was recovered from thereactor.

Similar results were obtained using fluorosulfonic acid (HOSO₃ F) orSnCl₄ instead of SbCl₅.

iii (Sulfolane Solvent)

Preparation of 1 -chloro-3,3,3-trifluoropropene from1,1,3,3-tetrachloropropene

A 450 ml hastelloy autoclave, fitted with a condenser and pressureregulator, was evacuated and cooled in a dry ice/acetone bath. Thecondenser was maintained at 0° C. The reactor was charged with 75 mltetramethylene sulfone (Sulfolane). The reactor was then cooled in a dryice/acetone bath and charged with 134 g (6.7 mole) of HF and 180 g (1.0mole) of 1,1,3,3-tetrachloropropene. The reactor was heated to 100° C.and the pressure maintained at 230 p.s.i. by venting HCl through theback pressure regulator. When HCl evolution ceased, the reactor wascooled to 70° C. and discharged through a KOH scrubber and into aseparatory funnel full of ice. The product was decanted as the moredense layer into a chilled bottle.

An average isolated yield of 115 g (86%) was achieved for each of 4consecutive runs. After washing, 2.3 g of oligomeric material wasrecovered from the reactor in each run.

Example 1b i (Catalyzed)

Preparation of 1,1,1,3,3-pentafluoropropane from1-chloro-3,3,3-trifluoropropene

(SbCl₅ Catalyzed)

A 300 ml hastelloy autoclave was charged with 35 g (0.12 mole) of SbCl₅and 48 g (2.4 mole) of HF. The reactor was heated to 80° C. for 1 hour.The reactor was then cooled to 20° C. and the pressure of HCl wasreleased. The reactor was then cooled in a dry ice/acetone bath andcharged with 68 g (3.4 mole) of HF and 140 g (1.04 mole) of1-chloro-3,3,3-trifluoropropene. The reactor was heated to 80° C. Afteran initial exotherm and a subsequent pressure increase, the reactor wascooled to 50° C. and discharged through a KOH scrubber and into aseparatory funnel full of ice. The product was decanted as the moredense layer into a chilled bottle.

An average of 112 g (76%) of 1,1,1,3,3-pentafluoropropane (71% purity)was isolated for each of 2 consecutive runs after which the catalystappeared to be inactive. 4 g of oligomers were observed on thiscatalyst.

ii (Catalyzed)

Preparation of 1,1,1,3,3-pentafluoropropane from1-chloro-3,3,3-trifluoropropene

(SbC₅ /TiCl₄ Catalyzed)

A 300 ml hastelloy autoclave was charged with 45 g (0.15 mole) of SbCl₅,7 g (0.04 mole) TiCl₄ and 24 g (12 mole) of anhydrous HF. The reactorwas heated to 90° C. for 1 hour. The reactor was then cooled to 20° C.and the pressure of HCl was released. The reactor was then cooled in adry ice/acetone bath and charged with 60 g (3.0 mole) of HF and 134 g(1.0 mole) of 1-chloro-3,3,3-trifluoropropene. The reactor was heated to90° C. After an initial exotherm and a subsequent pressure increase, thereactor was cooled to 50° C. and discharged through a KOH scrubber andinto a separatory funnel full of ice. The product was decanted as themore dense layer into a chilled bottle.

An average of 131 g (95%) of 1,1,1,3,3-pentafluoropropane was isolatedfor each of 2 consecutive runs. No oligomeric material was observed inthe reactor.

iii (Mixed Substrates)

Preparation of 1,1,1,3,3-pentafluoropropane from a Mixture of1,1,3,3-tetrachloropropene and 1,3,3,3-tetrachloropropene

A 450 ml hastelloy autoclave (reactor #1), fitted with a condenser andpressure regulator, was evacuated and cooled in a dry ice/acetone bath.The condenser was maintained at 0° C. The reactor was charged with 50 mltetraethylene sulfone (Sulfolane). The reactor was then cooled in a dryice/acetone bath and charged with 134 g (6.7 mole) of HF and 180 g (1.0mole) of about a 4 to 1 mixture of 1,1,3,3 and1,3,3,3-tetrachloropropene. The reactor was heated to 100° C. and thepressure maintained at 230 p.s.i. by venting HCl through the pressureregulator. When HCl evolution ceased, the reactor was cooled to 50° C.

A 300 ml hastelloy autoclave (reactor #2) was charged with 45 g (0.15mole) of SbCl₅, 7 g (0.04 mole) TiCl₄ and 24 g (1.2 mole) of anhydrousHF. The reactor was heated to 90° C. for 1 hour. The reactor was thencooled to 20° C. and the pressure of HCl was released. The reactor wasthen cooled in a dry ice/acetone bath. The 300 ml reactor was chargeddirectly with the contents of the 450 ml reactor (˜204 g). Any weightdeficit was made up with anhydrous HF. The reactor was heated to 90° C.After an initial exotherm and a subsequent pressure increase, thereactor was cooled to 50° C. and discharged through a KOH scrubber andinto a separatory funnel full of ice. The product was decanted as themore dense layer into a chilled bottle.

An average of 126 g (85%) of 1,1,1,3,3-pentafluoropropane (75% purity)was isolated for each of 8 consecutive runs. The remainder was1-chloro-1,3,3,3-tetrafluoropropane and1,1-dichloro-3,3,3-trifluoropropane (so-called underfluorinatedmaterials).

Reactor #1 contained a total of 45 g of oligomers after all 8 runs.Reactor #2 showed no evidence of tars.

Comparative Example

Reaction of Underfluorinated Materials

A 300 ml hastelloy autoclave, fitted with a condenser and pressureregulator, was charged with 45 g (0.15 mole) of SbCl₅, 7 g (0.04 mole)TiCl₄ and 48 g (2.4 mole) of anhydrous HF. The reactor was heated to 90°C. for 1 hour. The reactor was then cooled to 20° C. and the pressure ofHCl was released. The reactor was then cooled in a dry ice/acetone bathand charged with 136 g (6.8 mole) of anhydrous HF and 220 g (1.56 mole)of a mixture of 48% 1,1,1,3,3-pentafluoropropane, 32%1-chloro-1,3,3,3-tetrafluoropropane and 20%1,1-dichloro-3,3,3-trifluoropropane. The condenser was maintained at 0°C. The reactor was heated to 90° C. and the pressure maintained at 250p.s.i. by venting HCl through the pressure regulator. When HCl evolutionceased, the reactor was cooled to 60° C. and discharged through a KOHscrubber and into a separatory funnel full of ice. The product wasdecanted as the more dense layer into a chilled bottle.

An average of 200 g (93%) of 1,1,1,3,3-pentafluoropropane (98% purity)was isolated for each of 3 consecutive runs. No oligomeric material wasobserved in the reactor after all 3 runs.

Example 2

Separation of 1,1,1,3,3-Pentafluoropropane/Hydrofluoric Acid Mixture

A solution of 20 g of HF and 209 of 1,1,1,3,3-pentafluoropropane wasmade in a Teflon separatory funnel. The solution was chilled in an icebath and small amounts (see table below) of powdered sodium fluoridewere slowly added. The funnel was shaken and allowed to settle. Thelower organic layer was drawn-off, weighed and titrated with 0.5N sodiumhydroxide solution using phenolphthalein as the indicator.

    ______________________________________                                        Amount of NaF                                                                           0      0.42    0.84  1.26  1.68  2.10                               Added (grams)                                                                 Weight of 0      0       <1    7.10  10.60 13.40                              Organic Layer                                                                 (grams)                                                                       HF in     --     --      --    0.72  0.73  0.35                               Organic Layer                                                                 (grams)                                                                       ______________________________________                                    

I claim:
 1. A process for separating a fluorinated aliphatic hydrocarbonof the formula

    CH.sub.a F.sub.3-a --CH.sub.2 --CH.sub.b F.sub.3-b

wherein a is 0 or the integer 1 or 2 and b is 0 or the integer 1, 2 or3, from a hydrogen fluoride-containing reaction mixture said separationcomprising a. adding to said reaction mixture an organic or inorganicsalt thereby forming a mixture containing a separate phase enriched withsaid aliphatic fluorinated hydrocarbon and then separating from saidmixture said phase enriched with said aliphatic fluorinated hydrocarbon,said organic or inorganic salt beingI. unreactive to the componentscontained in the reaction mixture; ii. substantially insoluble in saidseparate phase that is enriched with said fluorinated aliphatichydrocarbon; and iii. separable from the mixture that is formed afterseparation of the phase enriched in said fluorinated aliphatichydrocarbon, and b. separating the fluorinated aliphatic hydrocarbonfrom the phase enriched in said fluorinated aliphatic hydrocarbon. 2.The process according to claim 1 wherein said organic salt is ammoniumfluoride or a lower alkyl ammonium fluoride.
 3. The process according toclaim 2 wherein said organic salt is ammonium fluoride or selected fromthe group consisting of mono, di, tri or tetra C₁ to C₃ linear orbranched alkyl ammonium fluoride.
 4. The process according to claim 3wherein said organic salt is ammonium fluoride, monomethylammoniumfluoride, dimethylammonium fluoride, monoethylammonium fluoride anddiethylammonium fluoride.
 5. The process according to claim 4 whereinsaid organic salt is ammonium fluoride.
 6. The process according toclaim 1 wherein the inorganic salt is a fluoride or a bifluoride of themetals of Group Ia of the Periodic Table of the Elements.
 7. The processaccording to claim 6 wherein said inorganic salt is a fluoride or abifluoride of an alkali metal selected from the group consisting oflithium, sodium and potassium.
 8. The process according to claim 7wherein said inorganic salt is a fluoride of sodium or of potassium. 9.The process according to claim 1 wherein quantity of organic orinorganic salt added to the reaction mixture is directly proportional tothe amount of fluorinated aliphatic hydrocarbon that appears in theenriched, liquid separate phase.
 10. The process according to claim 9wherein said quantity of organic or inorganic salt is from about 0.01mole of salt per mole of hydrogen fluoride to about 0.25 mole of saltper mole of hydrogen fluoride.
 11. The process according to claim 10wherein said quantity of organic or inorganic salt is from about 0 02mole of salt per mole of hydrogen fluoride to about 0.20 mole of saltper mole of hydrogen fluoride.
 12. The process according to claim 11wherein said quantity of organic or inorganic salt is from about 0.05mole of salt per mole of hydrogen fluoride to about 0.10 mole of saltper mole of hydrogen fluoride.